The present invention relates to the prevention of corrosion of coil-coated steel. More particularly, it relates to the prevention of cut-side corrosion using PVC-free coating compositions.
Coil-coated steel (often called pre-coated steel) is not coated on the cut sides, because it is cut after being coated. Corrosion can thus initiate at the cut sides, and progressively creep under the coating. Cut-side corrosion is a problem essentially in building uses, and to a lesser extent in white goods (refrigerators, washing machines and the like).
The best system presently known to prevent cut-side corrosion of coil-coated steel is based on polyvinylchloride (PVC) plastisol, and it is known that PVC is no longer considered as environmentally friendly for such use. An alternative solution is thus desired in the art, which should at least have equal resistance to cut-side corrosion.
It is an objective of the invention to provide a process for manufacturing PVC-free coil-coated steel having excellent cut-side corrosion resistance.
Another object of the invention is to provide a primer composition for a PVC-free coating system imparting excellent cut-side corrosion resistance of coil-coated steel.
Yet another object of the invention is to provide PVC-free coil-coated steel having excellent cut-side corrosion resistance.
These and other objects are provided by the invention as disclosed hereinafter.